The project represents a continuation of the investigation into the variables related to the development of the optical and refractive characteristics of the human and sub-human primate eyes. Since the work to date indicates that nearwork plays a considerable role in the development of myopic refractive characteristics, the present project will involve several approaches to the evaluation of its role. One is the longitudinal study of optical and refractive characteristic changes in Warm Springs, Oregon Indian children beginning at age five. The results obtained have been analyzed statistically and regression equations have been partially developed. As more information is gathered these equations will be modified in order to permit prediction of those individuals who will be come myopic and the point in time at which they will become myopic as well as the amount of myopia that will be achieved. The second approach involves the study of optical characteristics of monkeys subjected to different conditions of accommodation and/or convergence. When the intraocular pressure is monitored by an implanted pressure transducer of the radiosonde type, preliminary evidence suggests that there is an increase in vitreous chamber pressure which is linearly related to accommodation. We hope to be able to factor out the relationship and the contribution of both accommodation and convergence to this possible relationship.